OpenSystemsDevelopment / qpdf

Commit 44a13951940def9699b2c169e8a8eabd35973934

Authored by m-holger
1 parent 06a2d955

Refactor QPDF::Xref_table::read_entry and read_bad_entry 

Return results rather than using reference parameters.

Fixes bug in #1272 where parameters were not reinitialized when calling
read_bad_entry from read_entry.
Inline Side-by-side
Showing 2 changed files with 30 additions and 28 deletions
libqpdf/QPDF.cc
  View file @44a1395
... ... @@ -832,10 +832,6 @@ std::vector<QPDF::Xref_table::Subsection>
832 832 QPDF::Xref_table::bad_subsections(std::string& line, qpdf_offset_t start)
833 833 {
834 834 std::vector<QPDF::Xref_table::Subsection> result;
835   - qpdf_offset_t f1 = 0;
836   - int f2 = 0;
837   - char type = '\0';
838   -
839 835 file->seek(start, SEEK_SET);
840 836  
841 837 while (true) {
... ... @@ -844,7 +840,7 @@ QPDF::Xref_table::bad_subsections(std::string&amp; line, qpdf_offset_t start)
844 840 auto [obj, num, offset] = result.emplace_back(subsection(line));
845 841 file->seek(offset, SEEK_SET);
846 842 for (qpdf_offset_t i = obj; i - num < obj; ++i) {
847   - if (!read_entry(f1, f2, type)) {
  843 + if (!std::get<0>(read_entry())) {
848 844 QTC::TC("qpdf", "QPDF invalid xref entry");
849 845 throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")");
850 846 }
... ... @@ -890,9 +886,13 @@ QPDF::Xref_table::subsections(std::string&amp; line)
890 886 }
891 887 }
892 888  
893   -bool
894   -QPDF::Xref_table::read_bad_entry(qpdf_offset_t& f1, int& f2, char& type)
  889 +// Returns (success, f1, f2, type).
  890 +std::tuple<bool, qpdf_offset_t, int, char>
  891 +QPDF::Xref_table::read_bad_entry()
895 892 {
  893 + qpdf_offset_t f1{0};
  894 + int f2{0};
  895 + char type{'\0'};
896 896 // Reposition after initial read attempt and reread.
897 897 file->seek(file->getLastOffset(), SEEK_SET);
898 898 auto line = file->readLine(30);
... ... @@ -910,7 +910,7 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
910 910 }
911 911 // Require digit
912 912 if (!QUtil::is_digit(*p)) {
913   - return false;
  913 + return {false, 0, 0, '\0'};
914 914 }
915 915 // Gather digits
916 916 std::string f1_str;
... ... @@ -919,7 +919,7 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
919 919 }
920 920 // Require space
921 921 if (!QUtil::is_space(*p)) {
922   - return false;
  922 + return {false, 0, 0, '\0'};
923 923 }
924 924 if (QUtil::is_space(*(p + 1))) {
925 925 QTC::TC("qpdf", "QPDF ignore first extra space in xref entry");
... ... @@ -931,7 +931,7 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
931 931 }
932 932 // Require digit
933 933 if (!QUtil::is_digit(*p)) {
934   - return false;
  934 + return {false, 0, 0, '\0'};
935 935 }
936 936 // Gather digits
937 937 std::string f2_str;
... ... @@ -940,7 +940,7 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
940 940 }
941 941 // Require space
942 942 if (!QUtil::is_space(*p)) {
943   - return false;
  943 + return {false, 0, 0, '\0'};
944 944 }
945 945 if (QUtil::is_space(*(p + 1))) {
946 946 QTC::TC("qpdf", "QPDF ignore second extra space in xref entry");
... ... @@ -953,7 +953,7 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
953 953 if ((*p == 'f') || (*p == 'n')) {
954 954 type = *p;
955 955 } else {
956   - return false;
  956 + return {false, 0, 0, '\0'};
957 957 }
958 958 if ((f1_str.length() != 10) || (f2_str.length() != 5)) {
959 959 QTC::TC("qpdf", "QPDF ignore length error xref entry");
... ... @@ -967,18 +967,23 @@ QPDF::Xref_table::read_bad_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
967 967 f1 = QUtil::string_to_ll(f1_str.c_str());
968 968 f2 = QUtil::string_to_int(f2_str.c_str());
969 969  
970   - return true;
  970 + return {true, f1, f2, type};
971 971 }
972 972  
973 973 // Optimistically read and parse xref entry. If entry is bad, call read_bad_xrefEntry and return
974   -// result.
975   -bool
976   -QPDF::Xref_table::read_entry(qpdf_offset_t& f1, int& f2, char& type)
  974 +// result. Returns (success, f1, f2, type).
  975 +std::tuple<bool, qpdf_offset_t, int, char>
  976 +QPDF::Xref_table::read_entry()
977 977 {
  978 + qpdf_offset_t f1{0};
  979 + int f2{0};
  980 + char type{'\0'};
978 981 std::array<char, 21> line;
  982 + f1 = 0;
  983 + f2 = 0;
979 984 if (file->read(line.data(), 20) != 20) {
980 985 // C++20: [[unlikely]]
981   - return false;
  986 + return {false, 0, 0, '\0'};
982 987 }
983 988 line[20] = '\0';
984 989 char const* p = line.data();
... ... @@ -1002,7 +1007,7 @@ QPDF::Xref_table::read_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
1002 1007 if (!QUtil::is_space(*p++)) {
1003 1008 // Entry doesn't start with space or digit.
1004 1009 // C++20: [[unlikely]]
1005   - return false;
  1010 + return {false, 0, 0, '\0'};
1006 1011 }
1007 1012 // Gather digits. NB No risk of overflow as 99'999 < max int.
1008 1013 while (*p == '0') {
... ... @@ -1019,10 +1024,10 @@ QPDF::Xref_table::read_entry(qpdf_offset_t&amp; f1, int&amp; f2, char&amp; type)
1019 1024 // No test for valid line[19].
1020 1025 if (*(++p) && *(++p) && (*p == '\n' || *p == '\r') && f1_len == 10 && f2_len == 5) {
1021 1026 // C++20: [[likely]]
1022   - return true;
  1027 + return {true, f1, f2, type};
1023 1028 }
1024 1029 }
1025   - return read_bad_entry(f1, f2, type);
  1030 + return read_bad_entry();
1026 1031 }
1027 1032  
1028 1033 // Read a single cross-reference table section and associated trailer.
... ... @@ -1064,10 +1069,8 @@ QPDF::Xref_table::process_section(qpdf_offset_t xref_offset)
1064 1069 first_item_offset_ = file->tell();
1065 1070 }
1066 1071 // For xref_table, these will always be small enough to be ints
1067   - qpdf_offset_t f1 = 0;
1068   - int f2 = 0;
1069   - char type = '\0';
1070   - if (!read_entry(f1, f2, type)) {
  1072 + auto [success, f1, f2, type] = read_entry();
  1073 + if (!success) {
1071 1074 throw damaged_table("invalid xref entry (obj=" + std::to_string(i) + ")");
1072 1075 }
1073 1076 if (type == 'f') {
... ... @@ -1585,8 +1588,7 @@ QPDF::Xref_table::read_trailer()
1585 1588 {
1586 1589 qpdf_offset_t offset = file->tell();
1587 1590 bool empty = false;
1588   - auto object =
1589   - QPDFParser(*file, "trailer", tokenizer, nullptr, &qpdf, true).parse(empty, false);
  1591 + auto object = QPDFParser(*file, "trailer", tokenizer, nullptr, &qpdf, true).parse(empty, false);
1590 1592 if (empty) {
1591 1593 // Nothing in the PDF spec appears to allow empty objects, but they have been encountered in
1592 1594 // actual PDF files and Adobe Reader appears to ignore them.
... ...
libqpdf/qpdf/QPDF_private.hh
  View file @44a1395
... ... @@ -292,8 +292,8 @@ class QPDF::Xref_table
292 292 std::vector<Subsection> subsections(std::string& line);
293 293 std::vector<Subsection> bad_subsections(std::string& line, qpdf_offset_t offset);
294 294 Subsection subsection(std::string const& line);
295   - bool read_entry(qpdf_offset_t& f1, int& f2, char& type);
296   - bool read_bad_entry(qpdf_offset_t& f1, int& f2, char& type);
  295 + std::tuple<bool, qpdf_offset_t, int, char> read_entry();
  296 + std::tuple<bool, qpdf_offset_t, int, char> read_bad_entry();
297 297  
298 298 // Methods to parse streams
299 299 qpdf_offset_t read_stream(qpdf_offset_t offset);
... ...